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Continental Drift Theory

Continental Drift Theory. Alfred Wegener German meteorologist Found papers describing similar fossils on opposite sides of the Atlantic Researched more cases of similar organisms separated by oceans 1912 Proposed single supercontinent Pangaea.

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Continental Drift Theory

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  1. Continental Drift Theory • Alfred Wegener • German meteorologist • Found papers describing similar fossils on opposite sides of the Atlantic • Researched more cases of similar organisms separated by oceans • 1912 Proposed single supercontinent Pangaea

  2. Continental Drift Theory5 Types of Evidence • Fit of the Continents • Distribution of Fossils • Sequence of Rocks • Glacier Scraping Patterns • Ancient Climates and Wandering Polar Regions http://library.thinkquest.org/3669/media/map2dd.GIF

  3. Wegener’s Continental Drift Evidence: • Continents ‘fit’ together in a single land mass 250 mya • CLICK Simulations http://www.ucmp.berkeley.edu/geology/anim1.html http://www.eoearth.org/upload/thumb/f/fb/Plate_tectonics_over_time.gif/400px-Plate_tectonics_over_time.gif

  4. Wegener’s Continental Drift Evidence: Plant and animal fossils of the same species were found on several different continents.

  5. Wegener’s Continental Drift Evidence: Similar sequence of rockor rock formations have the same age

  6. Wegener’s Continental Drift Evidence: Glacial deposits, striations, and scraping patterns

  7. Wegener’s Continental Drift Evidence: Climate distribution Past Present Coal exists under the ice in the rock of Antarctica – yet coal can only form from plants that grow in warm climates.

  8. Wegener’s Theory Problems • Wegener had no convincing mechanism (did not explain the forces) of how the continents might move. Continents plowing through the crust would destroy the crust. • Continents are not moving apart at the speed Wegener proposed. Wegener = 250cm/yr Actual = 2 cm/yr

  9. Holmes Breakthrough: Heat trapped in the Earth caused convection currents in the mantle. • As a substance is heated its density decreases and rises to the surface until it is cooled and sinks again.

  10. Convection Currents • Gravity causes the heated mantle to sink • The mantle heats up near the core and then rises again • Conduction is the transfer of heat between 2 materials in direct contact with each other library.thinkquest.org/C003124/images/convect.jpg http://www.wisc-online.com/objects/index_tj.asp?objID=SCE304 Click animation

  11. Volcanic rocks on the seafloor have magnetization because, as they cool, magnetic minerals within the rock align to the Earth’s magnetic field. New Evidence: Magnetic pattern of rock

  12. North Magnetic Pole in No. Hemi

  13. North Magnetic Pole in So. Hemi

  14. Present DayNorth Magnetic Pole in No. Hemi

  15. Sea-Floor Spreading Hypothesis by Hess & Deitz CLICK Animation: http://www.uwsp.edu/geo/faculty/ritter/glossary/s_u/sea_flr_spread.html

  16. Plate Tectonics Theory Plates ‘float’ on the Asthenosphere Plates have oceanic and continental crust www.wiley.com/college/herenow/ptect/pt-map1.gif

  17. Earth’s Layers • Inner Core • Outer Core • Mantle • Crust • Atmosphere • Lithosphere – crust and upper mantle, plates move independently • Asthenosphere-region below the Lithosphere http://library.thinkquest.org/04oct/01724/images/Earth-crust-cutaway-english.png

  18. Continental Crust • Cooling rate - slow • Crystal size - large • Density – less dense • Thickest portion of the Earth’s outer layer • Composition – made mainly of granite rock http://www.amonline.net.au/geoscience/images/earth_diagrams/cont_oceanic_crust.gif

  19. Oceanic Crust • Cooling rate - fast • Crystal size - small • Density – more dense • Thinnest portion of the Earth’s outer layer • Composition – Made mainly of basalt rock http://faculty.weber.edu/bdattilo/parks/plume_ocean.jpg

  20. Volcano - opening or rupture in the Earth’s crust that allows molten rock to escape http://cgz.e2bn.net/e2bn/leas/c99/schools/cgz/accounts/staff/rchambers/GeoBytes%20GCSE%20Bl og%20Resources/Images/Plate%20Tectonics/Plate%20Tectonics/VolcanoStructure.jpg

  21. Earthquake - result of sudden energy release in the Earth’s crust creating seismic waves. • http://news.bbc.co.uk/nol/shared/spl/hi/world/04/earthquake/img/earthquake.gif

  22. More Evidence: Location of mountain ridges, rift valleys, mid-ocean ridges, and trenches on plate boundaries. Convergent, Divergent and Transform http://www.ifa.hawaii.edu/~barnes/ast110_06/tprai/Tectonic_plate_boundaries.png SIMULATIONS ON ALL BOUNDARY TYPES CLICK http://www.pbs.org/wgbh/aso/tryit/tectonics/shockwave.html

  23. Andes MountainsConvergent Oceanic & ContinentalPlates move toward each other Denser oceanic crust subducts under less dense continental crust A trench, a steep walled valley on the sea floor, forms here. blue.utb.edu/paullgj/images/Conv_Cont_Ocean.JPG CLICK http://www.pbs.org/wgbh/aso/tryit/tectonics/convergent.html

  24. Convergent BoundaryOceanic & Continental CLICK http://geology.com/nsta/convergent-boundary-oceanic-continental.gif http://geology.com/nsta/plate-tectonics-cover.gif

  25. Japan or Aleutian IslandsConvergent Oceanic & Oceanic Denser oceanic crust subducts under less dense oceanic crust ceeps.colostate-pueblo.edu/.../smM1P1Fig15.gif

  26. Convergent BoundaryOceanic & Oceanic http://geology.com/nsta/convergent-boundary-oceanic-oceanic.gif

  27. HimalayasConvergent Continental & Continental: Faulting and Folding http://www.pbs.org/wgbh/aso/tryit/tectonics/crush.html

  28. Convergent BoundaryContinental & Continental http://geology.com/nsta/convergent-boundary.gif

  29. Mid Atlantic RidgeDivergent Oceanic At a divergent boundary lithosphere plates move away from each other

  30. Divergent BoundaryOceanic • Mid-Ocean Ridges – a structure formed from seafloor spreading. CLICK http://geology.com/nsta/divergent-boundary-oceanic.gif

  31. East African Rift ValleyDivergent ContinentalRift Valley – Pulling apart of crust due to tensional forces ceeps.colostate-pueblo.edu/.../smM1P1Fig15.gif

  32. Divergent BoundaryContinental • Rift Valley http://geology.com/nsta/divergent-boundary-continental.gif

  33. San Andreas FaultTransform Plate BoundaryPlates slide past each other www.wiley.com/college/herenow/ptect/pt-map1.gif

  34. Transform Boundary TRANSFORM SIMUALTIONS CLICK http://geology.com/nsta/transform-boundary.gif CLICK http://www.pbs.org/wgbh/aso/tryit/tectonics/transform.htm

  35. http://vulcan.wr.usgs.gov/Imgs/Gif/PlateTectonics/Maps/map_plate_tectonics_world.gifhttp://vulcan.wr.usgs.gov/Imgs/Gif/PlateTectonics/Maps/map_plate_tectonics_world.gif Evidence - Location of earthquakes and volcanoes

  36. Hot Spots

  37. The Hawaiian-Emperor volcanic chain is the result of the drifting of the Pacific Plate over a fixed hot spot. http://geology.com/nsta/plate-tectonics-cover.gif

  38. The bend in the (Hawaiian – Emperor) volcanic chain is the result of a major change in the direction of the movement of the Pacific Plate.

  39. Location of Hot Spots Hot spots result from hot, narrow plumes of material that rise deep within the mantle.

  40. Plate Movement in the future • http://www.scotese.com/earth.htm It is even possible to measure the speed of continental plates extremely accurately, using satellite technology.

  41. External Energy For Earth • Sun & Moon keeps air and sea in motion, shapes surface • Sun warms atmosphere & crust unevenly creating winds • Winds drive ocean currents and water cycle • Erosion from winds, rains, rivers, glaciers, and waves shape surface • Weathering from winds and rains • Sun & Moon Gravitational Energy, produces tides • Planetesimal collisions

  42. Internal Energy for Earth • Radioactive element decay • Core heat from layers pressure • Convection currents • Volcanoes • Hot Springs • Earthquakes

  43. Evidence for Plate Tectonics First evidence used for Continental Drift Theory • Continents fit together • Fossil distribution • Common rock formations: same age • Glacier evidence: deposits, striations, scraping • Climate distribution New evidence • Magnetic pattern of rock • Location of earthquakes and volcanoes • Location of mountain ridges, rift valleys, mid-ocean ridges, and trenches

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